Some important applications of plate heat exchangers are i.a. a so-called flooded evaporator, which is used in large refrigerating machineries, and a droplet separator related thereto as well as condensers. A similar application is also heat pumps that use an evaporator and a condenser. Typically the evaporator and the condenser are located separately, inside separate outer casings. Building the evaporator and the condenser separate from each other increases i.a. manufacturing costs and the weight and size of the arrangement, whereby the space required by the arrangement is large. Typically also the droplet separator and the evaporator are arranged inside separate casing parts and the containers are preferably arranged one on top of the other. Also this increases the requirement of space for the arrangement and requires additional pipings in the apparatus.